I'm going on a little trip in a few weeks to visit a friend, and I was wondering if anyone knows if there are stores which sell bento gear (boxes and more) in Lausanne or Geneve (Switzerland).
I really hope so!

If you are looking for Japanese bento boxes, you can try taking a look at Globus (department store) - last time I checked they had a few, both in the Asian kitchenware section and in the camping section. Migros (look for MM or MMM sized ones - the Ms the bigger the store) does have some nice plastic boxes and such suitable for bentos. In addition, SIGG brand is sold in any sporting goods/camping goods store or department, and their boxes and bottles are very useful. The main Japanese grocery stores didn't have any bento boxes and stuff when I last visited, but they may be worth taking at look at anyway - see this list. (The last time I stopped by Mikado, they had more than half their space into an eat-in/takeout restaurant type place. They had sushi and bentos for sale.)